Its all fine! Just wanted to make sure its understood that i took care of that.
I had a look into the shader again to identify the described problem and sadly have to say there is nothing i can change about it at this point. At higher scales the whole raytracing just becomes to inprecise.
Therefore the density calcutlations get more and more rounded which probably leaves to these hard borders in the density. Same for the Ozone layer, but with it its much worse since the Color Ramp interpolation doesnt help with the whole problem either.
On large scale renders i suggest turning the ozone layer to zero to get better results for longer.
But generally i wouldnt suggest using Blender for real size renderings, its simply not made for that.